The present invention relates to a cleaning apparatus for use to remove a variety of sediments and rusts which might be created inside a pipe.
In installing telephone cables etc. in the earth, they are often laid by threading through existing steel pipes and cast pipes etc. which have been buried in the underground at the depth of 2-5 meters.
However, as an aging action after the laying of the pipes, a corrosion may take place inside such pipes, or deformation and detachment of such pipes may occur, and thereby making it difficult to thread the cables through the pipes. There are increasing cases that metal cables with greater diameters are used to meet an increasing demand by a telecommunication network, and thus cables may be prevented from being installed unless above-described problem inside the pipe is eliminated.
In this connection, it has been found that about 60% cases of troubles in which cables are prevented from being threaded through the pipes are attributable to a corrosion development inside the pipe, particularly on a joint area between adjacent pipes. Such corrosion may build-up on the pipe interior, and thus it may act to narrow down the pipe internal diameter.
Under such a situation, it has been customary in a prior art to take a continuity test initially so as to check for a presence of any abnormality inside the pipe, when new cables are to be installed in existing pipes, as described below.
This test is carried out in accordance with a prior art procedure illustrated in FIG. 10 wherein a wire 62 is connected with a mandrel 61 having a diameter slightly smaller than the internal diameter of the pipe, and then the mandrel 61 is inserted from a manhole into a horizontal pipe 60, as shown. The mandrel 61 is moved in one direction by pulling the wire 62, and then an inspection is made as to the presence of any abnormality inside the pipe 60. If the mandrel 61 can smoothly pass through the pipe 60 without any obstacle, it may be judged that the pipe retains its proper diameter, and thus additional cables may be installed smoothly.
On the contrary, if the mandrel 61 is prevented from advancing further or is immovable in any way, one can judge that the pipe internal diameter is narrowed down for the reason of some abnormality such as the corrosion development etc.
Traditionally, if it is suspected that the pipe interior may be corroded, then a remedial measure is taken in accordance with a procedure as described below in order to remove such corrosive build-up.
First, a pipe is threaded through an existing pipe, and then a high-pressure water stream (water jet) is injected from this pipe to wash away rust.
Secondly, a wire is connected with metallic or fiber brush, and the resultant assembly is then inserted into the pipe through a manhole. By pulling out one of the wires, the brush is caused to move through the pipe and thereby removing the rust which are created on the pipe interior surface.
However, the first method of using a high-pressure water stream has suffered from a problem that it requires a large capacity facility adequate to generate a water stream, and thus it entails a substantial amount of cost. Additionally, the prior art method was also problematic in that rusty materials were left unremoved from the pipe, since the water stream is deficient in removing large-sized rust. A further disadvantage of this method is that it needs a pipe camera to be inserted into the pipe to take a picture of the pipe interior and display it on a monitor screen to allow an operator to confirm the removal of rust.
The second method using the brush does not require any large capacity facility for use to remove the corrosion, and thus the method can be practised with less cost. Moreover, even a unskilled operator may carry out this procedure in a straightforward manner. However, this method is disadvantageous in that the rust which have been built-up in the pipe may not be removed perfectly merely utilizing frictional forces of the brush, and thus this method is often ineffective to increase and restore the pipe internal diameter to that as needed by the cable to be inserted.
Where a large quantity of rust is left unremoved in the pipe even after the cleaning operation was carried out in accordance with the procedure as above described, trouble-shooting procedures should be taken such as the re-excavation and repair of the pipe, replanning of the pipe laying route, and replacement of pipes being adopted etc. Consequently, a work period may be extended, which results in disadvantageously increased installation cost.
A particularly serious problem occurring from those prior arts is that an operator may not identify easily whether a corrosion development or any other phenomenon is a possible cause for narrowing down the pipe diameter. As a result, it frequently becomes necessary to use inexpensive pipe camera or carry out a cumbersome reexcavation operation in order to discriminate a cause by which the pipe diameter has been narrowed down.